Triple-expanded mechanical pipe coupling derived from a standard fitting

ABSTRACT

A coupling for joining pipe segments together is disclosed. The coupling is derived from a standard fitting and has a housing with a socket and a first expanded region adjacent to the socket, a second expanded region adjacent to the first expanded region and a third expanded region adjacent to the second. A sealing member is positioned in the first expanded region, a retainer is positioned in the second expanded region and a support washer having transversely oriented radial and coaxial flanges is positioned adjacent to the retainer in the third expanded region. A lip turned inwardly on the second expanded region overlaps the radial flange and captures the support washer, retainer and sealing member within the coupling. The retainer has a plurality of radial teeth angularly oriented to engage a pipe and prevent its removal from the coupling.

RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. application Ser. No. 10/123,607, filed Apr. 16, 2002, which is a continuation-in-part of U.S. application Ser. No. 10/007,951, filed Dec. 3, 2001, which is based on and claims priority of U.S. Provisional Application No. 60/262,820, filed Jan. 19, 2001.

FIELD OF THE INVENTION

[0002] This invention relates to couplings for pipes and especially to mechanical couplings derived from standard fittings which effect a strong, reliable joint with a fluid-tight seal without the need for brazing or soldering.

BACKGROUND OF THE INVENTION

[0003] The construction of piping networks requires couplings that can form fluid-tight joints between pipe ends which can withstand external mechanical forces, as well as internal fluid pressure and reliably maintain the integrity of the joint. Many forms of joints are known, such as brazed or soldered joints, threaded joints, welded joints and joints effected by mechanical means.

[0004] For example, copper tubing, which is used extensively throughout the world to provide water service in homes, businesses and industry, is typically joined by means of couplings which are soldered to the pipe ends to effect a connection.

[0005] The use of copper tubing for piping networks is so widespread that standard tubing sizes have been established in various countries. For example, in the U.S., there is the ASTM Standard; in Germany, the DIN Standard; and in the United Kingdom, the British Standard (BS). Chart 1 below shows a portion of the range of outer diameters of the various standard copper tubes listed above. Chart 1 Standard Outer Copper Tube Outer Diameters ASTM DIN BS ½″ 15 mm 15 mm ¾″ 22 mm 22 mm 1″ 28 mm 28 mm 1.25″ 35 mm 35 mm 1.5″ 42 mm 42 mm 2″ 54 mm 54 mm

[0006] Naturally, there are standard pipe fittings such as elbows (45° and 90°), tees and straight segments matched for use with the standard tube diameters. These standard fittings are defined in the U.S. by ASME Standard B16.22a-1998, Addenda to ASME B16.22-1995 entitled “Wrought Copper and Copper Alloy Solder Joint Pressure Fittings” dated 1998. The standard fittings have open ends with inner diameters sized to accept the outer diameter of a particular standard tube in mating contact for effecting a soldered joint.

[0007] In addition to the standard fittings described above, other components, such as valves, strainers, adapters, flow measurement devices and other components which may be found in a pipe network, will have a coupling which is compatible with the standard pipe, and it is understood that the term “coupling”, when used herein, is not limited to a standard elbow, tee or other fitting but includes the open end of any component useable in a piping network which serves to couple the component to the pipe end.

[0008] A soldered joint is effected between a standard diameter tube end and its associated standard fitting by first cleaning the surfaces to be joined, typically with an abrasive such as a wire brush or steel wool, to remove any contaminants and the oxide layer which forms on the surfaces. Next, the cleaned surfaces are coated with a flux material, usually an acid flux, which further disrupts the oxide layer (especially when heated) and permits metal to metal contact between the fitting, the pipe end and the solder. The pipe end is next mated with the fitting thereby bringing the cleaned, flux coated surfaces into contact. The fitting and pipe end are then heated to the melting temperature of the solder, and the solder is applied to the interface between the tube and the fitting. The solder melts, flows between the surfaces of the pipe end and the fitting via capillary action and upon cooling and solidifying forms the solder joint. Excess flux is removed from the outer surfaces to prevent further acid etching of the pipe near the joint.

[0009] While the soldered joint provides a strong, fluid-tight connection between pipe end and fitting, it has several disadvantages. Many steps are required to make the soldered joint, thus, it is a time consuming and labor intensive operation. Some skill is required to obtain a quality, fluid-tight joint. Furthermore, the solder often contains lead, and the flux, when heated, can give off noxious fumes, thus, exposing the worker to hazardous substances which can adversely affect health over time. The joint is typically heated with an open gas flame which can pose a fire hazard.

[0010] To overcome these disadvantages, many attempts have been made to create mechanical couplings which do not require solder or flame to effect a strong, fluid-tight joint. Such mechanical couplings often use an over-sized opening accommodating an O-ring for sealing purposes and an annular retainer interposed between the outer diameter of the pipe end and the inner diameter of the coupling to mechanically hold the parts together. The retainer often has radially extending teeth which dig into the facing surfaces of the coupling and the pipe end to resist extraction of the pipe end from the coupling after engagement.

[0011] While these mechanical couplings avoid the above identified problems associated with soldered joints, they can suffer from one or more of the following disadvantages. To be effective, the retainer requires sufficient space within the coupling. Thus, the couplings tend to be oversized relatively to the pipes they are intended to receive, and if existing standard couplings are to be adapted for use with such a mechanical system, it is usually necessary to adapt a larger size standard fitting to a smaller size standard pipe. This is more expensive than adapting the standard fitting appropriate to the standard pipe in what is known as a “size-on-size” fitting. For example, a standard ¾ inch pipe fitting may be used to couple a ½ inch standard copper pipe in a mechanical system (not “size-on-size”). Furthermore, the retainer may not provide adequate pull-out strength, and the pipe end could be inadvertently separated from the coupling, for example, during a pressure spike within the pipe, caused by a sudden closing of a valve (the “water hammer effect”) which places the joint under tension.

[0012] The retainer also does not help keep the pipe end coaxial with the coupling upon insertion, allowing the pipe end to tip and deform the retainer and gouge the inside surface of the coupling or an elastomeric seal, such as an O-ring. In such a mechanical joint, there is furthermore little or no resistance to axial rotation of the pipe relatively to the coupling (i.e., relative rotation of the pipe and coupling about the longitudinal axis of the pipe). Thus, valves or other items mounted on the pipe will tend to rotate. Mechanical joints with retainers also tend to have little resistance to bending, allowing the pipe too much angular free play and permitting the pipe to “walk” out of the joint under repeated reversed bending loads. Excessive free play also tends to disengage the teeth on one side of the retainer and deform the teeth on the other side, weakening the joint. Furthermore, use of an enlarged section to accommodate the retainer may cause energy loss impeding fluid flow if the fluid is forced to flow into a coupling having a larger cross-sectional area. In general, when mechanical couplings are designed to overcome the aforementioned inherent disadvantages, they tend to suffer from a high part count, making them relatively complex and expensive.

[0013] There is clearly a need for a mechanical pipe coupling which avoids the disadvantages of both soldered pipe fittings, as well as prior art mechanical fittings described above, and which can be derived from existing standard fittings and used with pipes appropriate to the standard fitting in a “size-on-size” association rather than using a larger size fitting to couple smaller diameter pipes together.

SUMMARY AND OBJECTS OF THE INVENTION

[0014] The invention concerns a pipe coupling having a socket with a diameter sized according to a standard to receive a pipe end having a diameter also sized according to the standard to be compatible with the socket. Preferably, the standard is ASME Standard B16.22a-1998, although other standards, such as the British Standard and the German DIN standard, are also contemplated.

[0015] The pipe coupling preferably comprises a stop surface positioned adjacent to one end of the socket, the stop surface extending radially inwardly and being engageable with the pipe end to prevent the pipe end from passing through the pipe coupling. A first expanded region is positioned adjacent to another end of the socket, the first expanded region having a larger diameter than the socket and sized to receive a sealing member, such as an elastomeric ring positionable therein for effecting a seal between the pipe coupling and the pipe end. A shoulder is positioned between the socket and the first expanded region, the shoulder being engageable with the sealing member when it is positioned in the first expanded region.

[0016] A second expanded region is positioned adjacent to the first expanded region, the second expanded region preferably having a larger diameter than the first expanded region and sized to receive a retainer positionable therein for retaining the pipe end within the pipe coupling. There may be a shoulder positioned between the first and second expanded regions. Preferably, the retainer comprises a ring sized to circumferentially engage the second expanded region (and the shoulder, when present), and a plurality of flexible, resilient, elongated teeth arranged circumferentially around the ring. The teeth project substantially radially inwardly from the ring and are angularly oriented in a direction away from the opening. The teeth are engageable circumferentially with the pipe end for preventing movement of the pipe end outwardly from the bore.

[0017] A third expanded region is positioned adjacent to the second expanded region, the third expanded region having a larger diameter than the second expanded region. There may be another shoulder positioned between the second and third expanded regions. The third expanded region forms an open end of the pipe coupling housing for receiving the pipe end. The third expanded region is sized to receive a support washer therein for supporting the pipe end. The support washer has a radially inwardly facing surface having a diameter substantially equal to and coaxial with the socket diameter for circumferentially engaging and supporting the pipe end. The two-point support provided by the socket and the support washer provides substantial resistance to bending of the pipe within the coupling. The support washer preferably has a circumferential collar which engages and supports the retainer.

[0018] A lip is positioned at the open end formed by the third expanded region, the lip extending substantially radially inwardly to be engageable with the support washer when it is positioned in the third expanded region. The various shoulders and the lip capture the sealing member, the retainer, and the support washer between one another. The lip may also be biased toward the socket so as to forcibly engage the support washer and clamp the washer within the third expanded region.

[0019] The invention also concerns a method of manufacturing a pipe coupling housing and a pipe coupling for receiving a pipe end. The method of making the housing comprises the steps of:

[0020] (A) providing a fitting having a socket;

[0021] (B) expanding a portion of the socket into a first expanded region having a larger inner diameter than the socket;

[0022] (C) expanding a portion of the first expanded region into a second expanded region having a larger inner diameter than the first expanded region; and

[0023] (D) expanding a portion of the second expanded region into a third expanded region having a larger inner diameter than the first expanded region, the third expanded region forming an open end for receiving the pipe end.

[0024] The following steps use the coupling housing to form the coupling:

[0025] (E) positioning a sealing member preferably within the first expanded region;

[0026] (F) positioning a retainer preferably within the second expanded region;

[0027] (G) positioning a support washer preferably within the third expanded region; and

[0028] (H) forming a lip extending substantially radially inwardly at the open end to capture the sealing member, the retainer and the support washer within the expanded regions.

[0029] Preferably, the socket is sized according to a standard.

[0030] It is an object of the invention to provide a mechanical pipe coupling which does not need to be soldered, brazed, welded, threaded or adhesively bonded to effect a joint.

[0031] It is another object of the invention to provide a standard mechanical pipe coupling which can be derived from existing standard pipe fittings.

[0032] It is still another object of the invention to provide a standard mechanical pipe coupling which can be used in a “size-on-size” association with an appropriate standard pipe for increased economy, improved fluid flow and compactness.

[0033] It is again another object of the invention to provide a standard mechanical pipe coupling which has substantial resistance to bending preventing excessive free play between pipe and coupling.

[0034] It is yet another object of the invention to provide a standard mechanical pipe coupling providing substantial resistance to axial rotation to inhibit rotation of valves and other components about the longitudinal axis of the pipe.

[0035] These and other objects and advantages of the invention will become apparent upon consideration of the following drawings and detailed description of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a partial longitudinal sectional view of a pipe coupling housing according to the invention;

[0037]FIG. 1A is a partial longitudinal sectional view of an alternate embodiment of a pipe coupling housing according to the invention;

[0038]FIG. 2 is a longitudinal sectional view of a pipe coupling according to the invention;

[0039]FIG. 3 is a front perspective view of a retainer according to the invention;

[0040]FIG. 4 is a rear perspective view of the retainer shown in FIG. 3;

[0041]FIG. 5 is an exploded perspective view of a pipe coupling in the form of an elbow fitting according to the invention; and

[0042]FIGS. 6 through 9 are partial longitudinal sectional views of various different embodiments of the coupling according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0043]FIG. 1 shows a pipe coupling housing 10 according to the invention having a socket 12 with an inner diameter 14 sized according to a standard to receive a pipe end sized, according to a compatible standard, to interfit within the socket 12. Preferably, coupling housing 10 is a modification of an existing standard pipe fitting, for example, an ASME Standard pipe fitting according to Standard number B16.22a-1998 for wrought copper and copper alloy solder joint pressure fittings. Fittings meeting the specification of other standards, such as the German DIN standard and the British BS standard, may also be modified to derive the coupling housing 10.

[0044] A stop surface 16 is positioned adjacent to one end 18 of the socket 12. Stop surface 16 extends radially inwardly and is, thus, engageable with an end of a pipe received within the socket to prevent the pipe end from passing through the coupling housing. Stop surface 16 is circumferentially continuous around housing 10, but may also be discontinuous as shown by stop surface 16 a in FIG. 1A.

[0045] A first expanded region 20 is positioned at the other end 22 of the socket 12, the first expanded region having a larger inner diameter 24 than the socket inner diameter 14. A shoulder 25 is positioned between the socket 12 and the first expanded region 20. The diameter 24 of the first expanded region is sized to receive a sealing member, the sealing member being engageable with the shoulder as described below.

[0046] A second expanded region 26 is positioned adjacent to the first expanded region 20. The second expanded region 26 has a larger inner diameter 28 than the inner diameter 24 of the first expanded region 20 and is sized to receive a retainer, also described below. A shoulder 27 is preferably positioned between the first and second expanded regions for engaging the retainer.

[0047] A third expanded region 29 is positioned adjacent to the second expanded region 26. The third expanded region 29 has a larger diameter 31 than the second expanded region and is sized to receive a support washer therein for supporting a pipe end as described below. Preferably a shoulder 33 is positioned between the second and third expanded regions, the shoulder 33 for engaging the support washer. The third expanded region 29 forms an open end 30 of the pipe coupling housing 10 for receiving the pipe end.

[0048] A lip 32 is positioned at the open end 30. The lip 32 extends radially inwardly from the third expanded region 29 and is engageable with the aforementioned support washer to capture and hold the support washer, retainer and sealing member within the coupling housing 10. The lip 32 may be biased toward socket 12 to forcibly engage the support washer and clamp it against the shoulder 33 within the third expanded region independently of the other components, such as the retainer and the sealing member.

[0049] Preferably, pipe coupling housing 10 is derived by die forming the socket of an existing standard pipe fitting to create the expanded regions 20, 26 and 29, the lip 32 being turned inwardly in a later operation after internal components such as the aforementioned sealing member, retainer and support washer are inserted into the coupling housing 10 to form a coupling according to the invention described in detail below.

[0050] While any standard fitting may be used as a starting point, the invention is particularly advantageously used with the ASME standard fittings compatible with copper tubing having a nominal diameter between {fraction (1/2)} and 2 inches. Similarly, the German and British standard fittings for copper tubing between 15 mm and 54 mm are also favored. It is understood that the invention is not limited for use with copper tube and could be applied to plastic or steel pipes and fittings for example. While it is advantageous to begin with a standard fitting from an economic standpoint, the coupling housing 10 could also be custom made for a particular application.

[0051]FIG. 2 shows a pipe coupling 40 according to the invention assembled from its various components including pipe coupling housing 10, a sealing member 42, a retainer 44 and a support washer 45. A pipe end 46 is shown in phantom line received within the coupling 40. Pipe end 46 is preferably a standard pipe, compatible with ASME Standard B16.22a-1998, for example, and the coupling housing 10 is preferably formed from a fitting originally designed according to the same standard to receive the pipe end 46 and modified by the formation of the expanded regions 20, 26 and 29 and the lip 32.

[0052] To realize economic advantage, it is preferable to modify a standard fitting intended originally for use with the diameter of the pipe end 46 and achieve a “size-on-size” relationship between the coupling and the pipe end. Size-on-size refers to the fact that the fitting being modified is for the size of pipe being coupled and not a fitting intended for a larger sized pipe which is then modified into a coupling which can take a smaller sized pipe.

[0053] As shown in FIG. 2, the inner diameter 14 of socket 12 is sized to receive and support the pipe end 46. Stop surface 16 engages pipe end to position it properly within coupling 40 and prevent it from passing through the coupling housing 10.

[0054] Sealing member 42, positioned adjacent to socket 12, is preferably an elastomeric ring having an angularly oriented circumferential surface 47 sloping toward the open end 30 of the coupling housing 10. Sloping surface 47 acts as a lead-in and helps prevent the sealing member from being pinched between the pipe end and shoulder 25. The sloping surface 47 also acts as a guide to align the pipe end 46 with the socket 12 and thus helps protect the seal from insertion damage due to misalignment between the pipe end 46 and the coupling 40. The sloping surface 47 also causes a reduction in the insertion force required to seat a pipe end 46 into the coupling 40. Sealing member 42 may also be an O-ring as shown in FIG. 6, or any other type of sealing member which will effect a fluid-tight joint between the pipe end and the coupling.

[0055] A fluid-tight seal is effected between the coupling housing 10 and the pipe end 46 by compressing the sealing member 42 in the annular space 48 between the outer surface 50 of pipe end 46 and the inside surface 52 of the first expanded region 20. Sealing member 42 seats against shoulder 25 which prevents it from moving deeper into the coupling housing 10 when pipe end 46 is inserted through opening 30 to engage the sealing member and be received in socket 12.

[0056] Retainer 44 is shown in detail in FIGS. 3 and 4 and comprises a ring 54 sized to engage the second expanded region 26 of coupling housing 10 (see FIG. 2). The ring seats within region 26 and stabilizes the retainer within the coupling housing. Preferably, coupling housing 10 has the second shoulder 27 which engages the ring 54 to properly position retainer 44 and prevent it from moving deeper into the coupling housing 10. In the absence of shoulder 27, the retainer 44 seats against the sealing member 42. Retainer 44 may also seat against an intermediate component as shown in FIG. 6 and described below.

[0057] Retainer 44 has a plurality of flexible, resilient teeth 60 which are arranged circumferentially around the ring 54 and extend substantially radially inwardly thereof. Teeth 60 are angularly oriented in a direction away from opening 30 (see FIG. 2) and are resiliently biased to engage outer surface 50 of pipe end 46. The angular orientation of teeth 60 allows the pipe end 46 to be received within opening 30 and pass through the retainer 44 and the sealing member 42 into socket 12 and seat against stop surface 16 but prevent withdrawal of the pipe end 46 outwardly from the coupling. Outward motion of the pipe end will tend to simultaneously compress and rotate the teeth inwardly thereby causing them to dig into the pipe outer surface 50 and retain the pipe within the coupling in a self-jamming manner such that, as greater force is applied to withdraw the pipe from the coupling the teeth 60 dig further and exert proportionally greater force to resist the outward motion until they bend or buckle.

[0058] As shown in FIGS. 3 and 4, ring 54 may have projections 58 extending radially outwardly. Projections 58 engage the second expanded region 26 and inhibit relative rotation between the retainer 44 and the coupling housing 10. Teeth 60 are biased forcibly against the outer surface 50 and dig into this surface to inhibit relative rotation between the pipe end 46 and the retainer 44. Together, the teeth 60 and the projections 58 inhibit relative rotation between the pipe end 46 and the coupling housing 10. Thus, valves or other items mounted on plain end pipe (i.e., pipe ends having no grooves or other modifications) by means of the coupling 40 will be less likely to rotate into an inconvenient or inaccessible position where they become difficult or impossible to actuate or service.

[0059] Preferred materials for the retainer include stainless steel to prevent corrosion, beryllium-copper alloys for excellent flexibility and strength and galvanic compatibility, as well as other resilient, flexible metals. Engineering plastics are also feasible.

[0060] Support washer 45, best shown in FIG. 2, preferably comprises a radially oriented circumferential flange 62 and a collar 64, also circumferential, but oriented transversely to the radial flange 62. Thus, support washer 45 has an “L”-shaped cross-section as shown which provides excellent torsional stiffness for support of the pipe end as described below. Radial flange 62 is in overlapping relation with and engaged by the lip 32 and thereby retained within the third expanded region 29. Preferably, the collar 64 extends inwardly of the pipe coupling housing 40 to support the teeth 60 against excessive deflection. By continuously supporting the teeth circumferentially around the coupling, the pull-out force required to remove the pipe end 46 from the coupling is increased because the teeth 60, when supported by the collar 64, will bend or buckle at a significantly higher load than when unsupported. The third expanded region 29 helps prevent rotational deflection of the support washer 45 when the lip 32 is turned inwardly to capture the washer 45, retainer 44 and sealing member 42 within the coupling. With significant rotation of the support washer 45 prevented, the collar 64 does not impinge on and deflect the teeth 60 radially outwardly away from the pipe end outer surface 50. If such outward radial deflection of teeth 60 were permitted it would reduce the effectiveness of the retainer at holding the pipe end within the coupling housing 10. The teeth 60 must be biased against the surface 50 to effectively engage and jam against the pipe end 46.

[0061] The collar 64 forms an inwardly facing surface 66 having an inner diameter 68 substantially equal to and coaxial with the inner diameter 14 of the socket 12. Together, the socket 12 and surface 66 engage and support the pipe end 46 when it is inserted into the coupling housing, the surface 66 and socket 12 providing a “two-point” support over a substantial length of the coupling housing. This two-point support afforded by the surface 66 and socket 12 provides substantial resistance to bending of the pipe end 46 within the coupling housing 10 and reduces free play of the pipe end. Increased bending stiffness and reduced free play help to ensure a reliable fluid-tight joint between the coupling 40 and the pipe end 46 which will not leak or come apart under repeated bending loads. Furthermore, the increased joint stiffness allows the same hanger spacing for mounting the pipe as used in a soldered joint system.

[0062] Preferred materials for the support washer include stainless steel to prevent corrosion and beryllium-copper alloys, as well as high strength engineering plastics.

[0063]FIG. 5 shows an elbow fitting 70 comprising a pipe coupling 40 according to the invention. As noted above, in addition to the straight through and elbow type couplings illustrated, any type fitting, such as a tee fitting, a fitting forming part of a valve, a sprinkler head, a filter or any other mechanical component, may be adapted to use a coupling according to the invention.

[0064]FIG. 5 presents an exploded view which is useful to describe how a coupling according to the invention is manufactured and used. Preferably, elbow fitting 70 begins as a standard fitting, for example, a standard ASME wrought copper or copper alloy solder joint pressure fitting according to ASME Standard B16.22a-1998 having a socket 12 sized to receive pipe end 46. Portions of the socket 12 are expanded, preferably by die-forming, into first, second, and third expanded regions 20, 26 and 29. Shoulders 25, 27 and 33 are preferably formed in the process of expanding the original socket 12. Next, sealing member 42 is positioned within the first expanded region 20, engaging shoulder 25. Retainer 44 is then positioned adjacent to the sealing member 42 in the second expanded region 26, engaging shoulder 27. Support washer 45 is next positioned in the third expanded region 29 adjacent to retainer 44 with collar 64 facing inwardly towards socket 12 for supporting teeth 60 on retainer 44 against excessive deflection. After the components are inserted and properly seated within the expanded regions, the lip 32, shown in phantom line, is formed by turning a portion of the second expanded region 26 radially inwardly to engage radial flange 62 of support washer 45 and capture the support washer, the retainer 44 and the sealing member 42 within the coupling 40. The lip 32 may be biased toward the socket 12 so as to forcibly engage and clamp the internal components in place. Lip 32 also forms opening 30 for receiving pipe end 46.

[0065] Coupling 40 thus formed is ready to receive a pipe end 46 in sealing engagement. Pipe end 46 may have a groove 72 cut or cold-formed in its outer surface 50 to engage teeth 60 of retainer 44 and provide additional gripping force preventing inadvertent separation of the pipe end from the fitting 70. The groove 72 may have knurling 74 or be otherwise textured to engage teeth 60 and prevent or at least inhibit rotation of the pipe end relative to the retainer. As described above, retainer 44 may have projections 58 extending outwardly from its ring 54 to engage the second expanded region 26 and prevent or inhibit rotation of the retainer 44 relative to the coupling 40. Together, knurling 74, teeth 60 and projections 58 help inhibit rotation of the pipe end 46 about its long axis 76 relative to the fitting 70. Thus, valves or other items mounted on the pipe by ,means of the coupling 40 will be less likely to rotate into an inconvenient or inaccessible position where they become difficult or impossible to actuate or service.

[0066] An additional groove 78 may also be formed in the pipe end 46 in spaced relation to the groove 72. The groove spacing is designed such that groove 78 aligns with flange 62 when the pipe end 46 is inserted into the coupling 40 to a depth sufficient for teeth 60 on retainer 44 to engage groove 72. Groove 78, thus, provides a visual indicator which allows the technician installing the pipe to immediately verify that the pipe end 46 is properly engaged with the coupling 40 to form a fluid-tight joint.

[0067] Plain end pipe (i.e., pipe ends having no grooves 72 or other modifications to increase pull-out strength) may also have a groove 78 or other form of witness mark, such as a score line, printed indicia and the like, which is positioned in spaced relation to the end of the pipe such that, when the witness mark aligns with flange 62 the pipe end 46 is substantially seated against the stop surface 16. The witness mark provides visual confirmation that the pipe end is properly and fully engaged with the coupling.

[0068] FIGS. 6-9 illustrate alternate embodiments of the pipe coupling according to the invention. In FIG. 6, coupling housing 10 has a sealing member 42 formed by an O-ring 80 positioned within the first expanded region 20. A washer 82 is positioned adjacent to the O-ring and retainer 44 is adjacent to the flat washer 82 in the second expanded region 26. Support washer 45 is positioned in the third expanded region 29 and has collar 64 for support of teeth 60 on the retainer 44. Lip 32 is in overlapping relation with radial flange 62 to capture the components within the coupling housing 10. Washer 82 separates and supports both the O-ring 80 and the retainer 44, allowing a relatively simple retainer design to be used which has only a ring 54 supporting teeth 60, thus, avoiding the need for a back flange on the retainer for engaging the O-ring.

[0069]FIG. 7 shows an embodiment of a coupling 40 wherein the collar 64 of the support washer 45 extends outwardly from the coupling housing 10 rather than inwardly toward the socket 12. This configuration provides the advantage of extending the length over which the coupling engages the pipe end, thus, further increasing the bending stiffness of the joint.

[0070]FIG. 8 shows a coupling 40 having a support washer 45 with a T-shaped cross section wherein the collar 64 extends both inwardly and outwardly from the housing 10. The extended collar of this embodiment provides both the increased bending stiffness of the embodiment of FIG. 7, as well as the support for teeth 60 of retainer 44, thereby providing higher pull-out loads for the pipe end.

[0071]FIG. 9 shows an embodiment of coupling 40 wherein the support washer 45 comprises a simple flat washer, the inner diameter 84 of the washer forming the inwardly facing surface 66 for support of the pipe end 46 as described above. Lip 32 engages the support washer 45 to capture and retain the other components such as the retainer 44 and the sealing member 42 within the coupling housing 10.

[0072] Couplings according to the invention provide a mechanical pipe coupling which can form a reliable fluid-tight joint without the hazards associated with brazing, welding or soldering while taking advantage of existing standard fittings in a size-on-size relationship with standard pipe to achieve significant economical advantage. 

What is claimed is:
 1. A pipe coupling housing having a socket with a diameter sized to receive a pipe end having a diameter sized to be compatible with said socket, said pipe coupling housing comprising: a first expanded region positioned adjacent to one end of said socket, said first expanded region having a larger diameter than said socket and sized to receive a sealing member positionable therein for effecting a seal between said pipe coupling housing and said pipe end, a first shoulder being positioned between said socket and said first expanded region, said shoulder being engageable with said sealing member when positioned in said first expanded region; a second expanded region positioned adjacent to said first expanded region and having a larger diameter than said first expanded region sized to receive a retainer therein for retaining said pipe end within said pipe coupling housing; a third expanded region positioned adjacent to said second expanded region and having a larger diameter than said second expanded region sized to receive a support washer therein for supporting said pipe end, said third expanded region forming an open end of said pipe coupling housing for receiving said pipe end; and a lip positioned at said open end and extending substantially radially inwardly to be engageable with said support washer when positioned in said second expanded region, said shoulders and said lip being adapted to capture said sealing member, said retainer and said support washer therebetween.
 2. A pipe coupling housing according to claim 1, wherein said lip is biased toward said socket for forcibly engaging said support washer and clamping it against said retainer.
 3. A pipe coupling housing according to claim 2, further comprising a second shoulder positioned between said first and said second expanded regions, said retainer and said support washer being clamped between said lip and said second shoulder.
 4. A pipe coupling housing according to claim 2, further comprising a third shoulder being positioned between said second and said third expanded regions, said support washer being clamped between said lip and said third shoulder.
 5. A pipe coupling housing according to claim 1, wherein said lip extends circumferentially around said open end.
 6. A pipe coupling housing according to claim 1, further comprising a stop surface positioned adjacent to another end of said socket opposite said one end, said stop surface extending radially inwardly and being engageable with said pipe end to prevent said pipe end from passing through said pipe coupling housing.
 7. A pipe coupling housing according to claim 1, wherein said socket is sized according to a standard.
 8. A pipe coupling housing according to claim 7, wherein said standard is ASME Standard B16.22a-1998.
 9. A pipe coupling housing according to claim 8, wherein said ASME Standard is for fittings compatible with copper tubing having a nominal diameter between {fraction (1/2)} inch and 2 inches inclusive.
 10. A pipe coupling housing according to claim 7, wherein said standard is a German DIN standard.
 11. A pipe coupling housing-according to claim 10, wherein said DIN Standard is for fittings compatible with copper tubing having a diameter between 15 mm and 54 mm inclusive.
 12. A pipe coupling housing according to claim 7, wherein said standard is a British Standard.
 13. A pipe coupling housing according to claim 12, wherein said British Standard is for fittings compatible with copper tubing having a diameter between 15 mm and 54 mm inclusive.
 14. A pipe coupling housing according to claim 1, wherein said coupling housing comprises an elbow fitting.
 15. A pipe coupling housing according to claim 1, wherein said coupling housing comprises a straight fitting.
 16. A pipe coupling sealingly engageable with a pipe end, said pipe coupling comprising: a coupling housing having a socket with a diameter sized to receive and circumferentially support said pipe end; a first expanded region positioned adjacent to one end of said socket, said first expanded region having a larger diameter than said socket; a first shoulder positioned between said socket and said first expanded region; a sealing member positioned in said first expanded region to effect a seal between said pipe coupling and said pipe end, said sealing member being engaged with said shoulder; a second expanded region positioned adjacent to said first expanded region, said second expanded region having a larger diameter than said first expanded region; a retainer interfitting within said second expanded region and being engageable circumferentially with said pipe end for retaining said pipe end within said pipe coupling; a third expanded region positioned adjacent to said second expanded region, said third expanded region having a larger diameter than said second expanded region and forming an open end of said coupling housing for receiving said pipe end; a support washer interfitting within said third expanded region between said retainer and said open end of said coupling housing; and a lip attached to said coupling housing and positioned at said open end, said lip extending substantially radially inwardly and overlapping and engaging said support washer to capture said support washer, said retainer and said sealing member between said shoulder and said lip.
 17. A pipe coupling housing according to claim 16, wherein said lip is biased toward said socket for forcibly engaging said support washer.
 18. A pipe coupling housing according to claim 17, further comprising a second shoulder positioned between said first and said second expanded regions, said retainer and said support washer being captured between said lip and said second shoulder.
 19. A pipe coupling housing according to claim 17, further comprising a third shoulder being positioned between said second and said third expanded regions, said support washer being clamped between said lip and said third shoulder.
 20. A pipe coupling housing according to claim 16, wherein said lip extends circumferentially around said open end.
 21. A pipe coupling according to claim 16, wherein said support washer has a radially inwardly facing surface having a diameter substantially equal to said socket diameter and coaxial therewith, said inwardly facing surface being circumferentially engageable with said pipe end upon insertion of said pipe end into said pipe coupling, said pipe end being supportable by said socket and said inwardly facing surface of said support washer.
 22. A pipe coupling according to claim 21, wherein said support washer comprises a circumferential flange and a circumferential collar arranged transversely to said circumferential flange, said circumferential flange being oriented substantially radially and in overlapping engagement with said lip, said circumferential collar being substantially coaxial with said socket and forming said inwardly facing surface for supporting said pipe end.
 23. A pipe coupling according to claim 22, wherein said circumferential collar extends outwardly from said open end of said coupling housing.
 24. A pipe coupling according to claim 22, wherein said circumferential collar extends inwardly of said pipe coupling toward said retainer for providing support thereto.
 25. A pipe coupling according to claim 22, further comprising a circumferential collar oriented transversely to said circumferential flange and extending outwardly from said open end of said coupling housing.
 26. A pipe coupling according to claim 16, further comprising a stop surface positioned adjacent to another end of said socket opposite said one end, said stop surface extending radially inwardly and being engageable with said pipe end to prevent said pipe end from passing through said coupling housing.
 27. A pipe coupling according to claim 16, wherein said socket has a diameter sized according to a standard to receive said pipe end, said pipe end also having a diameter sized to be compatible with said socket.
 28. A pipe coupling according to claim 27, wherein said standard is ASME Standard B16.22a-1998.
 29. A pipe coupling according to claim 28, wherein said ASME Standard is for fittings compatible with copper tubing having a nominal diameter between {fraction (1/2)} inch and 2 inches inclusive.
 30. A pipe coupling according to claim 27, wherein said standard is a German DIN standard.
 31. A pipe coupling according to claim 30, wherein said DIN Standard is for fittings compatible with copper tubing having a diameter between 15 mm and 54 mm inclusive.
 32. A pipe coupling according to claim 27, wherein said standard is a British Standard.
 33. A pipe coupling according to claim 32, wherein said British Standard is for fittings compatible with copper tubing having a diameter between 15 mm and 54 mm inclusive.
 34. A pipe coupling according to claim 16, wherein said coupling comprises an elbow fitting.
 35. A pipe coupling according to claim 16, wherein said coupling comprises a straight fitting.
 36. A pipe coupling according to claim 16, wherein said retainer comprises: a ring sized to circumferentially engage said second expanded region; and a plurality of flexible, resilient, elongated teeth arranged circumferentially around said ring, said teeth projecting substantially radially inwardly from said ring and being angularly oriented toward said socket, said teeth being engageable circumferentially with said pipe end for retaining said pipe end within said pipe coupling.
 37. A pipe coupling according to claim 36, wherein said support washer comprises a circumferential flange and a circumferential collar arranged transversely to said circumferential flange, said circumferential flange being oriented substantially radially and in overlapping engagement with said lip, said circumferential collar being substantially coaxial with said socket and extending inwardly of said pipe coupling toward said retainer, said circumferential collar for providing support to said teeth.
 38. A pipe coupling according to claim 36, wherein said teeth have a predetermined length so as to interfit within a groove formed circumferentially around said pipe end when said pipe end engages said socket, said teeth being engageable with said groove to increase resistance to movement of said pipe outwardly from said coupling.
 39. A method of manufacturing a pipe coupling housing for forming a pipe coupling for receiving a pipe end, said method comprising the steps of: providing a fitting having a socket; expanding a portion of said socket into a first expanded region having a larger inner diameter than said socket; expanding a portion of said first expanded region into a second expanded region having a larger inner diameter than said first expanded region; and expanding a portion of said second expanded region into a third expanded region having a larger inner diameter than said first expanded region, said third expanded region forming an open end for receiving said pipe end.
 40. A method according to claim 39, wherein said socket is sized according to a standard.
 41. A method of manufacturing a pipe coupling for receiving a pipe end, said method comprising the steps of: providing a fitting having a socket; expanding a portion of said socket into a first expanded region having a larger inner diameter than said socket; expanding a portion of said first expanded region into a second expanded region having a larger inner diameter than said first expanded region; expanding a portion of said second expanded region into a third expanded region having a larger inner diameter than said first expanded region, said third expanded region forming an open end for receiving said pipe end; positioning a sealing member within one of said expanded regions; positioning a retainer within another of said expanded regions; positioning a support washer within yet another of said expanded regions; and forming a lip extending substantially radially inwardly at said open end to capture said sealing member, said retainer and said support washer within said expanded regions.
 42. A method according to claim 41, wherein said socket is sized according to a standard.
 43. A method according to claim 41, wherein said sealing member is positioned within said first expanded region.
 44. A method according to claim 43, wherein said retainer is positioned within said second expanded region.
 45. A method according to claim 41, wherein said support washer is positioned within said third expanded region. 